JPH0394761A - Artificial supply and prosthesis material - Google Patents

Abstract

PURPOSE:To provide excellent bioaffinity and osteoplasty by mixing hydroxyapatite(HAP) and tricalcium phosphate(TCP) at a specific ratio and forming a sintered body. CONSTITUTION:The sintered body of the calcium phosphate consisting of the phase constitution in which the weight ratio of the hydroxyapatite(HAP) and the tricalcium phosphate(TCP) is 8/2 to 2/8 and the total content of both is >=90wt.% has excellent elutability and the extremely good bioaffinity. The elution quantity and elution rate of the calcium ions and phosphorus ions are changed by the ratio of the HAP/TCP in this case. The eluted calcium ions and phosphorus ions significantly influence the formation of bones. The substitution with the bones is highly accelerated if the HAP/TCP is 8/2 to 2/8 by weight.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a material for prosthetizing missing bones and teeth in humans and animals, and particularly to a calcium phosphate sintered body.

Conventional technology〉〈Problem to be solved by the invention〉
High-strength materials such as stainless steel and Aldanna porcelain have been used to replace lost human bones, teeth, etc., but they have poor affinity with living organisms and are difficult to bond with living organisms. Recently, alumina, apatite, crystallized glass, etc. have been studied, and some of them have been put into practical use.

Among them, apatite-based materials have good affinity with bones and are known to be easy to generate new bone. However, commercially available apatite-based materials are single hydroxyapatite or tertiary calcium phosphate, and are biocompatible. Although the affinity is good, bone formation is insufficient, and improvement in this point has been desired.

We conducted various studies on apatite sintered bodies and found that
As shown in Special Publication No. 60-50744, calcium/
Powder mainly composed of hydroxyapatite or tertiary calcium phosphate with a phosphorus atomic ratio of 1.4 to 1.75, and a specific amount of oxide-phosphoric acid frit such as alkali metal are added and mixed. It was also discovered that a sintered calcium phosphate sintered body with improved strength can be obtained. In addition, as shown in Japanese Patent Publication No. 60-25383, calcium phosphate is prepared by adding a specific amount of phosphoric acid to powder mainly composed of calcium phosphate with a calcium/phosphorus atomic ratio of 1.4 to 1.75, and sintering the mixture. It has been found that a sintered body can be obtained with improved strength.

Problems to be Solved by the Invention> However, all of the above-mentioned publications focus on the relationship between the composition before obtaining the sintered body and the strength of the sintered body; Regarding the structure itself, there is no suggestion as to what is the best structure in terms of biocompatibility and bone shape.

Means for Solving the Problems> The present invention was made as a result of various studies to solve this problem, and its outline is that hydroxyapatite (HAP) and tertiary calcium phosphate (TCP) are not used alone, but are It has been found that excellent effects can be exhibited by forming the material into a sintered body containing a mixed phase having a specific ratio.

In other words, the outline is that hydroxyapatite (HAP) and
Calcium phosphate (TCP) and HAP/TCP are 8/
It has been found that a calcium phosphate sintered body having a phase structure in which the total amount of both is 90% by weight or more has excellent dissolution properties and is extremely biocompatible.

In the above-mentioned phase structure, hydroxyapatite (HAP)
Since tertiary calcium phosphate (TCP) is used as a mixed phase, the elution amount and elution ratio of calcium ions and phosphorus ions change depending on the HAP/TCP ratio.

These eluted calcium ions and phosphorus ions greatly affect the shape of bones, and the weight ratio of HAP/TCP is 8/2 to 2.
It was found that the case of /8 greatly promotes bone replacement.

Effect> In the phase structure of the sintered body in the present invention, HAP/TC
P is preferably 8/2 to 2/8, but outside this ratio, H
If AP/TCP is greater than 8/2 and HAP/T
When CP is less than 2/8, no outflow occurs that matches the bone shape, and bone replacement is not very active.

In addition, when the total amount of HAP and TCP is 90% by weight or more, the biocompatibility increases and the bone replacement effect becomes active, but if it is outside this range and is less than 90% by weight, the bone replacement effect will be impaired. Not enough.

<Example> Example 1 Hydroxyapatite powder (wet rigid powder Ca/P=1.64
) with low Ca/P calcium phosphate glass frit (
Ca/P=0.5) was added in various amounts to precipitate tertiary calcium, and HAP/TCP was 10/0, 9/1, 8/
2, 5/5, 2/8, 1/9, 0/10 sintered grains (
A particle size of 400 to 600 μm) was obtained.

This was implanted into the jawbone of a monkey, sacrificed 6 months later, and the state of new bone formation around the granules was observed. In the case of the monkey, more new bone was observed than around the granule, but in this case, more new bone was observed than around the granule. Anything outside the scope of the invention was unsatisfactory. These results are shown in Table 1.

Table 1 Example 2 Granules (600 to 1000 μm) of variously modified HAP/TCP prepared in the same manner as in Example 1 were implanted into rat femurs, and sacrificed after 8 and 32 weeks. When bone formation was observed in the same manner as above, no significant difference was observed between those within the scope of the present invention and those of the comparative example at 8 weeks;
After 32 weeks, many new bones were observed in those using granules within the scope of the present invention.

The results are shown in Table 2.

Table 2 The results are shown in Table 3.

Table 3 Example 3 HAP and TCP combined by mechanochemical method were mixed in various ratios and sintered to obtain sintered grains, as described in Example 2 above.
When implanted in rat femurs in the same manner as above, sacrificed after 8 and 32 weeks, and observed the bone shape, there was not much difference at 8 weeks, but after 32 weeks, the bone shape of the present invention was significantly different. Good bone growth was observed.

According to the present invention, HAP/TCP is controlled from 8/2 to 2/4.
By containing 90% by weight or more of the constituent phases, it is possible to have better biocompatibility and bone formation than when each is used alone, and to exhibit the effect of promoting bone replacement. I can do it.

Claims (1)

[Claims] 1. An artificial prosthetic material in which the composition ratio of hydroxyapatite and tertiary calcium phosphate is 8/2 to 2/8 by weight, and the total amount of both is 90% by weight or more.